It's not that Gary Chang doesn't have room in his tiny flat to swing a cat. With just 344 square feet (32 square metres) of floor space, he doesn't have room for the cat.

Yet award-winning Hong Kong architect Chang has managed to squeeze 24 rooms -- including a steam room and home cinema -- into his Swiss army knife-style home.

Chang, 46, turned the tiny flat he has occupied since the age of 14 into what he calls his "domestic transformer," and in the process offered a vision for how one of the world's most densely-populated cities could better use its limited space.

"The key idea is that everyone could look into their home more carefully and into how better to optimise their resources, because space is a resource," he said.

"There is no use making your home as if it is a perfect show flat but at the same time never using the space," he said.

Chang has tackled the lack of room by replacing the flat's walls with a series of accordion-like sliding units, hung from metal tracks on the ceiling, that can be moved about to form a variety of configurations.

The partitions conceal drawers for clothes, shelves for toiletries and racks for thousands of CDs and DVDs.

Chang grabs a handle near his wall-mounted television and suddenly the wall itself is moving across the polished granite floor to the centre of the room, revealing a folding laminate worktop and well-stocked minibar facing the kitchen behind.

The flat can be one big, open-plan studio or, with very little effort, an arena of fold-down surfaces, seats and beds.

The concept was born of necessity. Growing up in the flat with six others, Chang had to be flexible.

"I have three younger sisters, so we all lived here. Originally there were three bedrooms, a living room and a dining room," he said.

"My sisters occupied one room, my parents another room and the third was actually not for me, it was for an outsider -- my parents sub-let it to somebody else to get more revenue. So actually I slept in the living room."

Chang still lives in the flat, and has spent his adult life reinventing his small corner of a 19-storey 1960s tower block in Hong Kong's bustling Sai Wan Ho district.

The architect believes his innovations can show even the poorest families how to improve their domestic arrangements and is determined that his book "My 32m2 Apartment: A 30-Year Transformation" will influence new housing.

Lack of space is a huge problem in Hong Kong, a metropolis of seven million, reflecting rocketing rental prices, at least before the recent downturn.

The average price per square metre nearly doubled from 32,777 dollars on Hong Kong island in 2002 to 58,915 dollars five years later, according to the city's housing authority.

But Chang regards the dense housing as a kind of social arbiter, responsible for some of the city's most notable virtues, such as low crime.

"Oddly enough, it's the lack of density that makes a place dangerous, because when the place is like Hong Kong, 24 hours it's busy and people feel safe," he said.

"It's like we are monitoring each other in quite a frequent manner so actually I try to argue for high density -- we have efficiency, convenience and security."

The optimisation of space means Chang can afford to squeeze in luxuries not usually seen in Hong Kong's tiny apartments, including a glass shower which doubles as a steam room, a 1.9-metre (six feet-three inch) bathtub and a reasonably sized kitchen.

There is even a wall-sized cinema screen, raised by remote control to reveal a huge, yellow-tinted window which gives the flat the illusion of being washed in warm sunlight, even on the cloudiest day.

Chang's experiment in flexible living began after he graduated from the University of Hong Kong, where he had been studying architecture.

"In the year I graduated, 1987, my parents moved to a better place in Hong Kong and my mother encouraged me to buy the place. So, starting in the late 1980s, it became my home," he said.

Chang has renovated four times, on each occasion with a bigger budget and more innovative approach, turning a 350,000-Hong Kong-dollar (45,000 US) shoebox into a mini-palace worth around 1.3 million dollars.